Pesticidal phosphorothioate compositions and methods of preparing them

ABSTRACT

The phosphorothioate pesticidal compositions O, O-diethyl O-(2isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, O,O-dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate and O,O-diethyl O-pnitrophenyl phosphorothioate are well known as agricultural pesticides; however, their high volatility and ready hydrolysis under ambient field conditions leads to substantial loss of the pesticide with a corresponding reduction in its effectiveness. The introduction of certain normally solid solutes having melting points below about 100* C into the pesticidal composition and the absorption of the resulting solution onto an inert porous carrier significantly reduces this problem. In addition, these and higher melting solutes may be dissolved in a volatile solvent, the phosphorothioate may be dissolved in a volatile solvent, the resulting solution may be absorbed onto an inert porous carrier, and the solvent volatized to provide useful phosphorothioate pesticidal compositions.

United States Patent Balassa PESTICIDAL PHOSPHOROTHIOATE COMPOSITIONSAND METHODS OF PREPARING THEM Leslie L. Balassa, Blooming Grove, NY.

[73] Assignee: Balchem Corporation, Slate Hill,

22 Filed: Jan. 22, 1971 21 Appl.No.: 109,062

Related US. Application Data [75] Inventor:

[52] US. Cl 424/200, 424/213, 424/218, 424/358 [51] Int. Cl A0ln 9/36[58] Field of Search 600/277; 795/73; 424/200, 196, 83, 213, 218, 358

[56] References Cited UNITED STATES PATENTS 2,996,426 8/1961 Galloway424/213 X 3,318,769 5/1967 Folckemer et a1 l 424/78 3,212,967 10/1965McFadden et al.. 424/78 2,529,681 11/1950 Flenner 424/354 3,089,8075/1963 Trademan et a1... 424/219 2,966,440 12/1960 Gerolt 424/278 OTHERPUBLICATIONS Ott, Emil Cellulose & Its Derivatives-lnterscience Pub.Inc., 1946, pp. 801-806.

[451 Sept. 25, 1973 Gregory, Thomas Uses & Applications of Chemical &Related Materials, Reinhold Pub., 1939, pp. 84 & 154-155.

Abraham, H. Asphalts & Allied Substances Nostand Pub., 1961, pp. 9, 10,172 & 173.

Pesticide Index, Frearl961, pg. 79.

Primary ExaminerAlbert T. Meyers Assistant ExaminerLeonard SchenkmanAttorney-Birch, Swindler, McKie & Beckett [57] ABSTRACT Thephosphorothioate pesticidal compositions O, O diethylO-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, 0,0-dimethylS-( 1,2-dicarbethoxyethyl) phosphorodithioate and 0,0-diethylO-p-nitrophenyl phosphorothioate are well known as agriculturalpesticides; however, their high volatility and ready hydrolysis underambient field conditions leads to substantial loss of the pesticide witha corresponding reduction in its effectiveness. The introduction ofcertain normally solid solutes having melting points below about 100 Cinto the pesticidal composition and the absorption of the resultingsolution onto an inert porous carrier significantly reduces thisproblem. In addition, these and higher melting solutes may be dissolvedin a volatile solvent, the phosphorothioate may be dissolved in avolatile solvent, the resulting solution may be absorbed onto an inertporous carrier, and the solvent volatized to provide usefulphosphorothioate pesticidal compositions.

18 Claims, No Drawings PESTICIDAL PHOSPHOROTHIOATE COMPOSITIONS ANDMETHODS OF PREPARING THEM This invention relates to agriculturalpesticides of the phosphorothioate type.

The phosphorothioate group of agricultural chemicals' and in particular0,0-diethyl O-(2-isopropyl-4- methyl-6-pyrimidinyl) phosphorothioate,0,0- dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate and0,0-diethyl O-p-nitrophenyl phosphorothioate have been found to be quiteeffective as pesticides; however, when applied to plants in the fieldduring the growing season, the effectiveness of the chemical dissipatesquickly. This has been traced to hydrolysis decomposition of thecompound, and to significant evaporation of the compound due to its highvapor pressure at the temperatures prevailing during the growing season.

It has now been found that certain specific compounds can be dissolvedin these phosphorothioate compounds so as to significantly suppress thevolatilization and hydrolysis of the compounds. The normal method ofintroducing the solute is to melt it together with the phosphorothioatecompound at an elevated temperature such as, for example, 80 C until allof the solute dissolves. A suitable inert porous carrier can then beblended into the mix to provide a normally solid composition containingthe phosphorothioate compound in effective amounts for slow release onapplication in the fields and which is not unduly dissipated underambient field conditions.

The solutes contemplated for the purposes of the present inventioninclude petroleum asphalts, the oxidized or blown petroleum asphalts,microcrystalline paraffin waxes, linear polystyrenes (including waxypolystyrene homopolymer and the co-polymers having styrene as a majorcomponent as well as the nuclear substituted polystyrenes) and ethylcellulose. All of these are generally solid at normal conditions(although some are tacky) but melt below about 100 C. The foregoingmaterials are selected for their solubility in and compatibility withthe particular phosphorothioate.

Of particular value for the purposes of the present in vention isoxidized petroleum asphalt, having a melting point range of l80-200 F.

Typical inert porous supports include such materials as vermiculite,expanded perlite, granulated corn cob and sintered clay granules. Afterthe melt has been suitably absorbed in the inner carrier, it ispreferably dusted using a suitable inert powder such as vermiculitepowder, powdered perlite, clay, talc and the like. Dusting of the finalparticle minimizes tackiness and thereby reduces the tendency of thepesticide-containing absorbent to agglomerate.

The chemical name, formula and trade-name for the phosphorothioatepesticides advantageously utilized in the present invention are setforth in Table I.

CzHaO While all three of the foregoing compounds are useful in thepractice of the present invention for simplicity the invention will beillustrated with the preferred compound, Diazinon.

EXAMPLE I Diazinon in an amount of 37.5 parts by weight and 12.5 partsby weight of oxidized asphalt (180/200 F melting point, Humble Oil andRefining Co.) were mixed and heated to about 80 C in an oil bath. Mixingwas continued until the asphalt completely dissolved in the Diazinon.Expanded vermiculite granules in an amount of about 40 parts by weightwere gradually added to the solution with constant mixing, whilemaintaining the temperature of the oil bath between about C. The mixingwas continued until the liquid was absorbed by the vermiculite. Thebatch was then cooled to about 20 C and about 10 parts by weight ofvermiculite powder added and distributed throughout the batch, therebycoating the surface of the granules. The product was then tested forrate of loss of Diazinon.

EXAMPLE 11 Example I was repeated except that petroleum asphalt having amelting point of 210 F (Pioneer 210 asphalt compound, Witco ChemicalCo.) was substituted for the oxidized asphalt.

EXAMPLE Ill The procedure of Example 1 was repeated except that thequantity of Diazinon was increased to 40 parts by weight and 10 parts byweight of microcrystalline wax (Multi-wax W-445 Witco Chemical Co.) wasemployed in place of the oxidized asphalt. Multi-wax W-445 is a mediummelting point white microcrystalline wax. The wax has a needlepenetration (ASTMD-l32l) at 77 F of 30, a melting point (ASTM D-l27) of173 F and a Saybolt viscosity, SUS (ASTM D-88) at 210 F of 85.

EXAMPLE IV Example 111 was repeated except that polystyrene resin (Dowresin PS-2) was substituted for the microcrystalline wax. Thepolystyrene was a solid at room temperature and was soluble in andcompatible with the Diazinon. The polystyrene resin, Dow resin PS-2, hasan average molecular weight of 22,000, a viscosity (30 percent solutionin toluene) cps. of 12 to 20 and a softening range, F, of to 200.

EXAMPLE V Example [[1 was repeated except that ethyl cellulose (7 cpsgrade, Hercules, Inc.) was substituted for the microcrystalline wax;

EXAMPLE VI This was a control example using 50 parts by weight ofDiazinon, 40 parts by weight of expanded vermiculite granules and 10parts by weight of expanded verm iculite powder. The procedure was thesame as for Example I.

EXAMPLES VII VIII Following the procedure of Example I, beeswax andcarnauba wax were substituted for the oxidized asphalt. The resultingproduct had properties corresponding to those found with Example Il.

PRODUCT TESTING Two gram samples of the products of Example I .throughVI were placed in separate aluminum dishes TABLE II Material Percentagelost during hours exposed 48 Hrs. 72 Hrs. 150 Hrs.

Example-l 0 1 Example ll 0 3 I76 Example III 6 6 9 Example IV 6 I05 llExample V v 6 9 ll Example VI I8 23 28 As will be seen from Table II,dissolving the various solutes in the pesticidal composition greatlyreduced the tendency of the pesticide to volatilize and/or hydrolyzeprematurely. The slow release is sufficent to maintain the pesticidalactivity of the composition over a far longer period of time than waspreviously possible, thereby permitting economy in usage and asignificant reduction in the number of applications necessary to protecta field from pests. Indeed, after 150 hours of exposure, the compositionof Example I lost only 1 percent due to volatilization and hydrolysis,whereas the control sample lost 28 percent. It will, therefore, furthcrbe seen that oxidized asphalt is the preferred solute for the purposesof the present invention.

Accordingly, for the purposes of the present invention, the preferredcomposition comprises expanded vermiculite granules in which there hasbeen absorbed a substantial quantity of a solution of a major amount ofthe phosphorothioate chemical Diazinon, and a minor amount of oxidizedasphalt, particularly when the final product is then again blended withexpanded vermiculite powder. The relative proportions are not critical.Obviously, there should be at least a significant proportion ofpesticide contained in the vermiculite, e.g., at least 5 percent. As apractical matter, however, the relative proportions of the pesticideshould be substantially greater up to the point of maximum absorption bythe inert carrier. Similarly, the amount of the particular solute addedto the pesticide is not critical. A very slight amount of the solutewill provide a slight improvement inthe overall properties of thecomposi tion. In general, there should be on the order of at least 1percent, and generally there should be in excess of 5 percent. Amountsmuch in excess of percent will not provide a significant improvement inproperties. Thus, the amounts shown in the examples represent theoptimum concentrations of the solute. The amount of the powdered inertcarrier material is not critical but need merely be sufficient toprevent undue glomeration of the particles and undue tackiness of theoverall final product.

In using the product of the present invention as a pesticide, theproduct is dusted on to the growing plants in the same manner and at thesame growth stages as these phosphorothioates have been applied in thepast. The quantity of pesticide applied in a single field treatment doesnot difi'er significantly from prior dosages. The main difference isnoted in the number of treatments required; thee present inventionrequires very substantially reduced number of applications due to itslonger period of effectiveness.

While the foregoing procedure very significantly protects thephosphorothioate pesticide against excessive loss due to evaporationand/or decomposition or degradation due to hydrolysis, a significantdegree of decomposition or degradation is still observed. This remainingdecomposition and/or degradation has been found to result frommicrobiological attack. Warm, moist soil always contains bacteria andfungus which attack the phosphorothioates. In prior phosphorothioatecompositions, the loss of phosphorothioate due to volatilization andhydrolysis were so great that microbiological attack was not apredominant concern. The frequent applications of the phosphorothioatepesticides compensated for the loss of pesticide. The great resistanceof the compositions of the present invention to volatilization andhydrolsis permits the retention of the compositions in contact with thesoil for extended periods of time without the necessity for frequentapplications. In this new method of application, therefore,microbiological attack can become significant.

Accordingly, the inclusion of very small quantities of bactericidal orbacteriostatic and fungicidal or fungistatic materials, when properlyemployed in combination with the solute disclosed previously herein, caneffectively protect the composition against microbiological attack andthus extend still further the effective life of the pesticidalcomposition. In general, an amount of from about 0.01 percent to about10 percent (by weight, based on solvent free insecticidal composition)of these materials has been found useful for this purpose.

Examples of the agents useful for minimizing microbiological attack areas follows:

Copper compounds copper salts of long chain fatty acids, includingcopper oleate, copper stearate and copper octoate; copper naphthenate;and copper 8- hydroxy-quinolinolate.

Phenol compounds phenol and the oil or hydrocarbon solvent solublephenols and derivatives; halophenols, particularlyo-benzyl-p-chlorophenol (Santophen I made by the Monsanto ChemicalCompany); ophenylphenol; chloro-ortho-phenylphenol; pentachlorophenol;tetra-chlorophenol; chloroxylenol; chlorocresol; chlorobenzylphenol;methylene-bis (trichlorophenol); and the salts of the foregoing whichare soluble in the pesticides; alkyl phenols having an alkyl group of2-28 carbon atoms in the molecule including the various cresols, 0-, andpethyl phenol, p-isopropyl phenol, p-tertiary-butyl phenol,2-methyl-4-dodecyl phenol, o-hexadecyl phenol.

Organo-mercury compounds phenyl-mercury octo-- the granular composition.The preferred method, how-.

ever, is to include the additive in the matrix or in thephosphorothioate for maximum effectiveness.

Coal tar, pitch and wood creosote contain sufficient of the abovephenolic compounds to provide the desired bacteriostatic and fungistaticproperties to be suitable as part or all of the protective material forthe phosphorothioate pesticides. Coal tar pitch additionally possessessufficient moisture resistance to serve as the sole protective agentagainst both hydrolysis and microbiological degradation. Accordingly,coal tar pitch is one of the preferred agents for incorporation in thecomposition of the present invention.

Expanded vermiculite, as noted previously, is the preferred carrier forlow density granules of the composition of the present invention.Degradation of phosphorothioates may, in some instances, be acceleratedin the presence of natural clay granules. If granules of higher densitythan are obtainable with vermiculite are desired, high temperaturecalcined and acid washed clay granules can be employed. Additionally,pigmentextender grade barium sulfate (barytesor blanc-fixe) calcined atabout 1,100 C to form porous granules also serves as a satisfactorycarrier for phosphorothioate pesticides. Calcined clay granules whichhave been pretreated with materials for reducing the catalytic activitesof clays, for example, diethylene glycol, can also be used as a carrierfor the purposes of the present invention.

In all of the foregoing examples, the protective solutes had meltingpoints below about 100 C. This was necessary due to the manner of mixingthe solutes with the phosphorothioate compounds, viz, melt mixing.Higher temperature melts could, on mixing with the insecticides, lead tosignificant decomposition of the phosphorothioate. This problem can beavoided, however, by utilization of readily volatilizable solvents whichwill dissolve and be compatible with both the phosphorothioate and theprotective solute. Typically, the materials are dissolved in thesolvent, and the phosphorothioate is added at a temperature well below100 C, the porous carrier is impregnated with the solution and thesolvent is evaporated at elevated temperature not exceeding about 100 C.The following examples typify this procedure.

The following examples illustrate preferred embodiv ments of the presentinvention.

The oxidized asphalt used in this composition was a petroleum asphaltwith a melting point of 180/220 F and was supplied by the Humble OilRefining Company. The oxidized asphalt and the cupric oleate weredissolved in the toluene at about 60 C. The toluene solution was cooledto below 50 C and the Diazinon added and mixed.

The expanded vermiculite was placed in a jacketed ribbon blender, heatedto about 40 C and the Diazinon solution was sprayed on the surface ofthe vermiculite while the blender was continuously operated. When allthe solution was added, the operation of the blender was continued foran additional 10 minutes to complete the impregnation of the vermiculitegranules by the solution. The toluene was stripped from the material byevaporation at about 40 C.

EXAMPLE x Example IX was repeated except that no copper oleate was used,and 10 percent of the asphalt was replaced by an equal weight of coaltar.

EXAMPLE X1 Example X was repeated except that the coal tar was replacedby an equal weight of wood creosote.

EXAMPLE XII The following composition was prepared:

Parts by weight o-benzyl-p-chlorophenol 2 0 The o-benzyl-p-chlorophenolused in this example was Santophen I of Monsanto Chemical Company whilethe Pioneer Asphalt, a petroleum asphalt, was supplied by the WitcoChemical Company. The o-benzyl-p-chlorophenol was dissolved in thetoluene. The asphalt was heated in an oven to C, a temperature slightlyhigher than its melting point. The toluene was then added in incrementsto the molten asphalt with constant mixing until a homogeneous solutionwas obtained. The toluene lost by evaporation was replaced and thetemperature of the solution was lowered to about 50 C and the Diazinonwas added with constant mixing. The homogeneous solution was mixed withthe acid washed clay which was preheated to about 40 C. The toluene wasthen stripped atreduced pressure at about 40 C.

EXAMPLE XIII Example XII was repeated except that the carrier in thiscase was granular calcined barytes.

EXAMPLE XIV The following composition was prepared:

Copper Naphthenate (Cu 6%) Camauba wax flakes 25.0 Toluene 100.0Diazinon 25 .0 Corn Cob granules 225.0 Total 376.0

The corn cob granules used in this Example were Grade No. 10/30(Grit-)'Cob supplied by D. Anderson of Maumee, Ohio. The carnauba waxwas molten and the toluene was mixed with the molten wax and the mixingcontinued until a clear solution was obtained. The copper naphthenatewas then added and the temperature of the solution lowered to about 60C. The

Diazinon was then added and mixed. The resulting homogeneous solutionwas mixed with the corn cob grits at about 60 C.

EXAMPLE XV Example XIV repeated with the carnauba wax re placed by anequal weight of an ozokerite wax (l-Ioeschst Wax S) and the copperoleate by the same weight of pentachloro-phenol.

EXAMPLE XVI Example IX was repeated but with copper oleate held out ofthe composition. The copper oleate was applied by spraying a 2 percenttoluene solution of it to the surface of the granular composition. Thetoluene was stripped from the material at about 50 C and at reducedpressure.

EXAMPLE XVII Example XII was repeated but with theo-benzyl-pchlorophenol held out and applied to the granular compositionby spraying a 2 percent hexane solution of it to the surface of thegranules. The hexane was allowed to evaporate from the granular materialin a slow current of air at room temperature.

EXAMPLE XVIII Example XVII was repeated except that the solution of theo-benzyl-p-chlorophenol was absorbed on finely powdered expandedvermiculite, and then the solvent substantially evaporated from thepowder. The dry powder, containing about 5 percento-benzyl-pchlorophenol was then dusted to the surface of the granularcomposition to result in 0.1 percent of chlorophenol based on the totalweight of the granular composition.

The products of Examples IX and XVIII were tested in greenhouse tests intopsoil obtained from corn fields. The tests were conducted up to nineweeks at 30 C and 90 percent humidity and at a pesticide level of 0.05of the pesticide composition on the weight of the dry soil. The residualkill ratio for insects and insect larvae were determined at 1, 3, 5, 7and 9 weeks. Insects and larvae included in these tests were comrootworm, cutworm and wireworm. As a control, the same insecticides wereapplied to the same carrier at the same concentration as thecorresponding test sample. Secondary controls were the same insecticidescombined with the same solutes as the test sample but without thebactericide or fungicide used in the test sample. a

All primary controls lost their activity in l to 3 weeks. The secondarycontrols showed reduced activity after three weeks and loss of activityin the five weeks test. The samples represented by the examples showedfull insect killing activity for seven weeks and only slight loss ofactivityin the 9 weeks tests.

EXAMPLE XIX A solution was prepared by dissolving 25 parts by weight ofa maleic-modified resin ester (Lewisol 28, a product of HerculesChemical Co.) which had a melting point of l4l C., and 25 parts byweight of Diazinon in 100 parts by weight of benzene at 30 C. Thesolution was absorbed on 225 parts by weight of calcined clay-sericitegranules which are sold commercially under the name "Tru-sorb." Thismaterial comprises calcined clay-sericite granules, commonly of 24 48mesh (Tyler) grain size, and has a typical chemical analysis as follows:

Spectographic analysis confirmed the chemical analysis and additionallyindicated a small titanium content and traces of lithium, copper,chromium and manganese. The material exhibits a pH of 7-7.2, has adensity of 38 lbs/ft and a lube oil absorbency of 79 percent.

The solution-impregnated granules were dried in a current of air atabout 40 C., until substantially all of the benzene had evaporated. Theresulting product, when applied to surface soil, retains itsinsecticidal activity in the upper 10 cm. of soil with little or noleaching loss to depths below about 12.5 cm. even three weeks afterfield application.

EXAMPLE XX Example XIX was repeated except that the maleicmodified resinester was replaced by an equal amount of a phenolic-modifiedpentaerythritol ester of resin (Pentalyn 802A, manufactured by HerculesChemical Corporation) which had a melting point of C. The product hasproperties essentially the same as the product of Example XIX.

EXAMPLE XXI Example XIX was repeated except that the maleicmodifiedresin ester was replaced by an equal amount of a glycerol ester ofpolymerized resin (Poly-Polo Ester l0 manufactured by Hercules ChemicalCorpora tion) which had a melting point of 114 C. The product hasproperties essentially the same as the product of Example XIX.

It will be seen from the foregoing that the resinous and/or waxymaterials useful as solute protectants for the purposes of the presentinvention may be described as members of the group of waxes, resins,bitumens, tars and pitches, many of which are described in the precedingexamples. In addition, typical waxes include carnauba, beeswax,candelilla and other vegetable and insect waxes, hydrogenated fatty-acidglycerides, hydrogenated castor oil, ozokerite (Hoeschst Wax S) andoxidized ozokerite waxes (X-22 of I-Ioeschst Chemical Co.) and theirmodifications, paraffin waxes, oxidized paraffin waxes, andmicrocrystalline waxes (Multi-wax W-445, Witco Chemical Co.). Typicalresins include wood and gum resin, resin esters, e.g., pentaerythritolester of resin (Pentalyn 255 of Hercules Chemical Co.) terpene resins(Piccolite A-l 15 of Pennsylvania Industrial Chem. Corp.), gum damar,gum copal alkyd resins, oil modified alkyds, polystyrene (Dow resinPS-2), polyacrylates and polymethacrylates, cellulose esters and ethers(ethyl cellulose, 7 cps grade, Hercules Chemical Co.) polyvinyl estersand ethers and shellac. Typical bitumens include gilsonite, petroleumasphalt (Pioneer and Pioneer 220 of Witco Chemical Co.), oxidizedasphalt HBO/200 F melting point, Humble Oil and Refining Co.). Typicaltars and pitches include coaltar and coaltar pitches, wood creosote,wood pitch, and bone pitch.

What is claimed is:

l. A pesticidal composition consisting essentially of an inert porouscarrier on which is absorbed a solution of about 1 to about 15 percentof a normally solid petroleum asphalt having a melting point below about100 C in a phosphorothioate pesticide selected from the group consistingof 0,0-diethyl -(2-isopropyl-4- methyl-6-pyrimidinyl) phosphorothioate,0,0-dimethyl S-( l ,2-dicarbethoxyethyl) phosphorodithioate and 0,0-diethyl o-p-nitrophenyl phosphorothioate, said composition having aminimization of losses of said pesticide due to hydrolysis andvolatilization under ambient field conditions.

2. The composition of claim 1 which additionally contains about 0.01about weight percent based upon the weight of the composition of amember selected from the group consisting of bactericides andfungicides.

3. A pesticidal composition consisting essentially of an inert porouscarrier on which is absorbed a solution of about 1 to about percent of anormally solid oxidized petroleum asphalt having a melting point belowabout 100 C in a phosphorothioate pesticide selected from the groupconsisting of 0,0-diethyl 0-(2-isopropyl- 4-methyl-6-pyrimidinyl)phosphorothioate, 0,0- dimethyl S-(1,2-dicarbethoxyethyl)phosphorodithioate and 0,0-diethyl O-p-nitrophenyl phosphorothioate,said composition having a minimization of losses of said pesticide dueto hydrolysis and volatilization under ambient field conditions.

4. The composition of claim 3 which additionally contains about 0.01 toabout 10 weight percent based on the weight of the composition of amember selected from the group consisting of bactericides andfungicides.

5. A pesticidal composition consisting essentially of an inert porousgranular carrier material in which is impregnated an evaporated solutionof a phosphorothioate pesticide selected from the group consisting of0,0- diethyl O-(2-isopropyl-4-methyl -6-pyrimidinyl) phosphorothioate,0,0-dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate and0,0-diethyl O-p-nitrophenyl phosphorothioate and about 1 to about 15percent of a normally solid petroleum asphalt in a compatiblevolatilizable solvent which is capable of being volatilized at atemperature below about 100 C, said pesticide, said petroleum asphaltand said carrier material being in intimate association with each other.

6. A pesticidal composition consisting essentially of an inert porousgranular carrier material in which is impregnated an evaporated solutionof a phosphorothioate pesticide selected from the group consisting of0,0- diethyl 0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate,0,0-dimethyl S-(l,2-dicarbethoxyethyl phosphorodithioate and 0,0-diethylO-p-nitrophenyl phosphorothioate and about 1 to about 15 percent of anormally solid oxidized petroleum asphalt in a compatible volatilizablesolvent which is capable of being volatilized at a temperature belowabout 100 C, said pesticide, said petroleum asphalt and said carriermaterial being in intimate association with each other.

7. A process of preparing an improved phosphorothioate pesticide foragricultural use, the improvement being a minimization of losses of saidpesticide due to hydrolysis and volatilization under ambient fieldconditions, comprising dissolving in a phosphorothioate pesticideselected from the group consisting of O, O- diethylO-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethylS-( l, 2-dicarbethoxyethyl) phosphorodithioate and O, O-diethylO-pnitrophenyl phosphorothioate, a minor amount of from about 1 to about15 percent of a normally solid petroleum asphalt having a melting pointbelow about C and absorbing the resulting solution on an inert porouscarrier.

8. The process of claim 7, wherein said phosphorothioate pesticide is O,O-diethyl O-(2-isopropyl-4-methyl- 6-pyrimidinyl) phosphorothioate.

9. The process of claim 7, wherein said inert porous carrier is expandedvermiculite.

10. A process of preparing an improved phosphorothioate pesticide foragricultural use, the improvement being a minimization of losses of saidpesticide due to hydrolysis and volatilization under ambient field conditions, comprising dissolving in a phosphorothioate pesticide selectedfrom the group consisting of O, O- diethylO-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethylS-(l, Z-dicarbethoxyethyl) phosphorodithioate and O, O-diethylO-pnitrophenyl phosphorothioate, a minor amount of from about 1 to about15 percent of a normally solid oxidized petroleum asphalt having amelting point below about 100 C and absorbing the resulting solution onan inert porous carrier.

11. The process of claim 10 wherein said inert porous carrier isexpanded vermiculite.

12. The process of claim 10 wherein said phosphorothioate pesticide isO, O-diethyl O-(2-isopropyl-4- methyI-G-pyrimidinyl) phosphorothioate.

13. A process for preparing a phosphorothioate pesticide selected fromthe group consisting of O, O-diethylO-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethylS-(l, Z-dicarbethoxyethyl) phosphorodithioate, and O, O-diethylO-p-nitrophenyl phosphorothioate for agricultural pesticidal use,comprising dissolving said phosphorothioate, pesticide and a minoramount of from about 1 to about 15 percent of a water insoluble,normally solid, non reactive petroleum asphalt in at least onevolatilizable solvent which is capable of being volatilized at atemperature below about 100 C, absorbing the resulting solution on aninert, porous, granular carrier material and evaporating said solvent toprovide a composition comprising said phosphorothioate, said petroleumasphalt and said carrier material being in intimate association witheach other.

14. The process of claim 13, wherein said phosphorothioate pesticide isO, O-diethyl O-(2-isopropyl-4- methyl-6-pyrimidinyl) phosphorothioate.

15. The process of claim 13, wherein said inert porous carrier isexpanded vermiculite.

16. A process for preparing a phosphorothioate pesticide selected fromthe group consisting of O, O-diethylO-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethylS-(l, 2-dicarbethoxyethyl) phosphorodithioate, and O, O-diethylO-p-nitrophenyl phosphorothioate, for agricultural pesticidal use,comprising dissolving said phosphorothioate pesticide and a minor amountof from about 1 to about 15 percent of a water insoluble, normallysolid, non reactive oxidized petroleum asphalt in at least onevolatilizable solvent which is capable of being volatilized at atemperature below about 100 C, absorbing the resulting solution on aninert, porous, granular carrier material and evaporating said solvent toprovide a composition com- 1 1 l2 prising said phosphorothioate, saidoxidized petroleum 18. A process in accordance with claim 16 whereinasphalt and said carrier material being in intimate asso- Saidphosphorothioate pecticide is 0, Odiethfl ciation with each other. 7

17. A process in accordance with claim 16 wherein said inert porouspowder is expanded vermiculite.

isopropyl-4-methyl-6-pyrimidinyl phosphorothioate.

2. The composition of claim 1 which additionally contains about 0.01 about 10 weight percent based upon the weight of the composition of a member selected from the group consisting of bactericides and fungicides.
 3. A pesticidal composition consisting essentially of an inert porous carrier on which is absorbed a solution of about 1 to about 15 percent of a normally solid oxidized petroleum asphalt having a melting point below about 100* C in a phosphorothioate pesticide selected from the group consisting of 0,0-diethyl 0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, 0,0-dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate and 0,0-diethyl 0-p-nitrophenyl phosphorothioate, said composition having a minimization of losses of said pesticide due to hydrolysis and volatilization under ambient field conditions.
 4. The composition of claim 3 which additionally contains about 0.01 to about 10 weight percent based on the weight of the composition of a member selected from the group consisting of bactericides and fungicides.
 5. A pesticidal composition consisting essentially of an inert porous granular carrier material in which is impregnated an evaporated solution of a phosphorothioate pesticide selected from the group consisting of 0,0-diethyl 0-(2-isopropyl-4-methyl -6-pyrimidinyl) phosphorothioate, 0,0-dimethyl S-(1,2-dicarbethoxyethyl) phosphorodithioate and 0,0-diethyl 0-p-nitrophenyl phosphorothioate and about 1 to about 15 percent of a normally solid petroleum asphalt in a compatible volatilizable solvent which is capable of being volatilized at a temperature below about 100* C, said pesticide, said petroleum asphalt and said carrier material being in intimate association with each other.
 6. A pesticidal composition consisting essentially of an inert porous granular carrier material in which is impregnated an evaporated solution of a phosphorothioate pesticide selected from the group consisting of 0,0-diethyl 0-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate, 0,0-dimethyl S-(1,2-dicarbethoxyethyl phosphorodithioate and 0,0-diethyl 0-p-nitrophenyl phosphorothioate and about 1 to about 15 percent of a normally solid oxidized petroleum asphalt in a compatible volatilizable solvent which is capable of being volatilized at a temperature below about 100* C, said pesticide, said petroleum asphalt and said carrier material being in intimate association with each other.
 7. A process of preparing an improved phosphorothioate pesticide for agricultural use, the improvement being a minimization of losses of said pesticide due to hydrolysis and volatilization under ambient field conditions, comprising dissolving in a phosphorothioate pesticide selected from the group consisting of O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethyl S-(1, 2-dicarbethoxyethyl) phosphorodithioate and O, O-diethyl O-p-nitrophenyl phosphorothioate, a minor amount of from about 1 to about 15 percent of a normally solid petroleum asphalt having a melting point below about 100* C and absorbing the resulting solution on an inert porous carrier.
 8. The process of claim 7, wherein said phosphorothioate pesticide is O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate.
 9. The process of claim 7, wherein said inert porous carrier is expanded vermiculite.
 10. A process of preparing an improved phosphorothioate pesticide for agricultural use, the improvement being a minimization of losses of said pesticide due to hydrolysis and volatilization under ambient field conditions, comprising dissolving in a phosphorothioate pesticide selected from the group consisting of O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethyl S-(1, 2-dicarbethoxyethyl) phosphorodithioate and O, O-diethyl O-p-nitrophenyl phosphorothioate, a minor amount of from about 1 to about 15 percent of a normally solid oxidized petroleum asphalt having a melting point below about 100* C and absorbing the resulting solution on an inert porous carrier.
 11. The process of claim 10 wherein said inert porous carrier is expanded vermiculite.
 12. The process of claim 10 wherein said phosphorothioate pesticide is O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate.
 13. A process for preparing a phosphorothioate pesticide selected from the group consisting of O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethyl S-(1, 2-dicarbethoxyethyl) phosphorodithioate, and O, O-diethyl O-p-nitrophenyl phosphorothioate for agricultural pesticidal use, comprising dissolving said phosphorothioate, pesticide and a minor amount of from about 1 to about 15 percent of a water insoluble, normally solid, non reactive petroleum asphalt in at least one volatilizable solvent which is capable of being volatilized at a temperature below about 100* C, absorbing the resulting solution on an inert, porous, granular carrier material and evaporating said solvent to provide a composition comprising said phosphorothioate, said petroleum asphalt and said carrier material being in intimate association with each other.
 14. The process of claim 13, wherein said phosphorothioate pesticide is O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate.
 15. The process of claim 13, wherein said inert porous carrier is expanded vermiculite.
 16. A process for preparing a phosphorothioate pesticide selected from the group consisting of O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl) phosphorothioate; O, O-dimethyl S-(1, 2-dicarbethoxyethyl) phosphorodithioate, and O, O-diethyl O-p-nitrophenyl phosphorothioate, for agricultural pesticidal use, comprising dissolving said phosphorothioate pesticide and a minor amount of from about 1 to about 15 percent of a water insoluble, normally solid, non reactive oxidized petroleum asphalt in at least one volatilizable solvent which is capable of being volatilized at a temperature below about 100* C, absorbing the resulting solution on an inert, porous, granular carrier material and evaporating said solvent to provide a composition comprising said phosphorothioate, said oxidized petroleum asphalt and said carrier material being in intimate association with each other.
 17. A process in accordance with claim 16 wherein said inert porous powder is expanded vermiculite.
 18. A process in accordance with claim 16 wherein said phosphorothioate pecticide is O, O-diethyl O-(2-isopropyl-4-methyl-6-pyrimidinyl phosphorothioate. 